1. Field of the Invention
The present invention relates to a detecting device for deposited metals on soldering points on a substrate of an integrated circuit board, particularly a ball grid array (BGA) integrated circuit (IC) board substrate, to thereby detects defect with respect to the lack of deposited metals for soldering points on the substrate.
2. Description of the Related Art
A ball grid array integrated circuit (BGA IC) packaging method is a newly developed method for ICs with a quantity of pins and is suitable for packaging ultra-large scale integration (ULSI) produced by submicron solution. In such a packaging method, divided single chips are secured on the substrate of the BGA IC, and a package encapsulant is provided to enclose the IC chips projecting beyond the surface of the substrate.
The soldering points on the substrate of the above-mentioned BGA IC form a ball grid array. A deposited metal is formed in advance for each soldering point in order to allow easy subsequent formation of a tin ball on each soldering point. If the deposited metal is not properly deposited, the tin ball tends to be disengaged from the substrate and thus results in a defective product. The packaging process is the last process in integrated circuit manufacture. Disengagement of the tin ball causes a waste in production, as the signal function of the chips on the IC will be adversely affected. The defect index can be largely reduced if the deposited metals that act as tin ball pads can be detected in advance.
Conventionally, the deposited metals on the soldering points on the BGA IC are detected by human vision with an aid of a magnifier, which is slow and apt to have misjudgment due to eye-strain or personnel error.
As a result of progress in computer and image input device and technique therefor, detection by computer analysis in the images of computer elements has been utilized in industry, and an example of which is disclosed in Taiwan Patent Publication No. 305940 that discloses an apparatus and method for detecting integrated circuits. In this Taiwan Patent Publication No. 305940, light beams from a light base are switched to illuminate the integrated circuit elements. The shadows thus generated are reflected with a number of lenses to capture the shadow images of the IC elements. The shadow images of the pins of the IC elements are transmitted to the computer for analysis. This, the image identifying technique by computer is used to replace eye detection and applied to detect deposited metals for soldering points on the substrate of BGA IC.